Carbon Footprint Calculators Don’t Make Sense

The carbon footprint calculators make no sense to us when it comes to the calculations for Jet travel.

Lets run some numbers.

A Boeing 737 burns 800 gallons of fuel per hour

A gallon of jet fuel weighs just less than 7 pounds

In a five-hour flight that is 4000 gallons of fuel weighing 28,000 pounds

Or 14 tons of jet fuel

The 737 will carry up to 162 passengers.Lets assume 80% capacity or 130 in a typical flight

Here is what does not make sense to us:

That works out to 0.107 tons of fuel per person (about 200 pounds of fuel per person)

Yet according to their Carbon Calculators that same 5-hour flight produces the following TONS of carbon per person:

ZeroFootPrint.com2.71 Tons p/ person(24 times the weight of the fuel)

CarbonFootPrint.com.496 Tons p/person(2.5 times the weight of the fuel)

Green.yahoo.com2.0 Tons p/person(20 times the weight of the fuel)

How can this possibly be?Certainly the vast majority of the fuel is converted to energy.How is it possible that the jet fuel produces many more times as much carbon as the weight of the fuel itself? Never mind the question as to why all of these calculators give us such wildly different calculations. Something is wrong here or are we missing something?

One Response

While the footprint calculations may seem quite off, what these measure is CARBON DIOXIDE weight, and not just carbon. So while there is less than 14tons of carbon in a jetliners worth of fuel (made up of nearly all just carbon and hydrogen… carbon being much heavier than hydrogen), once mixed and burned with oxygen the carbon dioxide output of the jet engines ends up being many more tons heavier than the jetfuel alone. Oxygen is #8 on the periodic table, Carbon is #6… so in a CO2 molecule, about 3/4 of the molecular weight is from the oxygen… So carbon dioxide output of a jet engine should be about 250-300% more in tonage than the fuel going in…